Water-swellable clays that have acceptable water-swellability and colloidal properties, e.g., the non-blue bentonites having a Fe.sup.+3 /Fe.sup.+2 ratio above 1.0, and preferably above 3.0, have a great number of industrial uses that rely upon the ability of the clay to absorb many times its weight in water. Such water-swellable clays, such as sodium bentonite, however, lose much of their absorbency if the water absorbed is contaminated with water-soluble metal salts of alkali metals or alkaline earth metals, particularly the sulfate or halide salts, such as sodium chloride, magnesium chloride, calcium bromide, calcium chloride, potassium chloride, salt-containing body fluids and the like. Some bentonite clays, such as the blue bentonites disclosed in Clem U.S. Pat. No. 2,672,442, require the uptake of calcium ions to provide acceptable water swellability and colloidal properties for industrial acceptance. The preferred water-swellable clays useful as starting materials in accordance with the present invention are non-blue bentonites (green to greenish yellow to yellow to cream colored) that have industrially acceptable water swellability and colloidal properties and have a Fe.sup.+3 /Fe.sup.+2 ratio greater than 1.0, preferably at least 3.0, and most preferably in the range of about 5.0 to about 15.0. Some of these industrial uses for the treated water-swellable clays of the present invention, where once dried water-swellable clays, e.g., sodium bentonite, have their absorbency adversely affected upon contact with salt-contaminated water, are described as follows.